Conductive liquid compositions are used in the production of semiconductor packages and microelectronic devices and in assembly, for various purposes including antistatic functions, electromagnetic wave shield functions and anisotropic conductive adhesive functions (die mounting adhesives and the like).
With the introduction of flexible display terminals in recent years, and as conventional electronic terminals continue to decrease in thickness, the substrates that are coated with conductive liquid compositions are becoming ever more diverse and include different types of flexible plastic substrates and thin glass substrates.
Furthermore, as thicknesses decrease as is above described, the coating layers of the conductive liquid compositions are also becoming thinner, and for solid patterns with low thicknesses of about 5 to 10 μm and wide areas (for example, about 50 mm×80 mm), it is becoming increasingly difficult to achieve uniform and highly smooth surfaces for the conductive liquid composition coating layers, which has resulted in the problem of variation in conductive functioning at the coating layer locations.
Incidentally, the surface smoothness of a coated film tends to be improved when the conductive liquid composition coating layer is a thick film of about not less than an extent from 15 to 25 μm, but this solution not only increases the amount of conductive liquid composition used and results in higher cost, but also interferes with the aforementioned decrease in thickness.
In light of this situation, the performance required for conductive liquid compositions naturally includes the ability for a single type of conductive liquid composition to be used in common for plastic substrates including flexible sheets and the like and conventional glass, and a conductive function that ensures adequate performance for the purpose even with a low film thickness, as well as a high leveling property (surface smoothness) to exhibit a uniform conductive function without fine irregularities even with thin coated films, and the ability to adequately withstand rinsing with MEK and the like that are used for removal of trace contamination. However, it is clear from the prior art literature cited below that, as of the current time, no conductive liquid composition has yet been developed that simultaneously exhibits the aforementioned required performance to a satisfactory extent.
Prior Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2015-230847) discloses metal covered particles with high conductivity and a conductive resin composition containing the metal covered particles, but it does not disclose technology relating to a conductive liquid composition that can be used in common for plastic substrates and glass substrates, nor does it disclose technology relating to formation of a coated film with a high degree of surface smoothness even as a thin-film, and able to adequately withstand organic solvent rinsing.
Prior Patent Document 2 (Japanese Patent Public Inspection No. 2016-513143) discloses technology relating to a conductive ink composition that is satisfactory for flexible film substrates, but it does not disclose technology allowing common use for glass substrates as well, or technology relating to formation of a coated film with a high degree of surface smoothness even as a thin-film, and able to withstand organic solvent rinsing.
Prior Patent Document 3 (Japanese Patent Public Inspection No. 2010-539650) discloses a conductive composition including a binder and filler particles with a silver plated core, the composition having a sheet resistivity of not more than about 0.100 Ω/sq./25 μm, but it does not disclose technology allowing common use for both plastic substrates and glass substrates, or technology relating to formation of a coated film with a high degree of surface smoothness even as a thin-film, and able to withstand organic solvent rinsing.
Prior Patent Document 4 (Japanese Patent Public Inspection No. 2011-526309) discloses a conductive curable composition filled with a silver-coated flaky material, the disclosure also relating to the viscosity and thixotropic property of the composition. However, it does not disclose technology allowing common use for both plastic substrates and glass substrates, nor does it disclose technology relating to formation of a coated film with a high degree of surface smoothness even as a thin-film, and able to withstand organic solvent rinsing.